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COUNTERPOINT HYBRID PHONO STAGE UPGRADE

This is my first post, but I am well acquainted with this forum. I have recently imported a SA 5000 from a member and I am very impressed with the build quality, and performance of the line stage. It is a vast improvement over my modified SA 3. I have both service and owner's manuals, and the documentation is equally impressive, and worth the asking price.
I intend to do some of the Alta Vista upgrades, and would like to remove the JFET and inductor from the cathode circuit of the phono 1st gain stage as a starting point, and replace with a resistor, using the low gain common-cathode triode option for MM cartridge only.
I have no philosophical objection to hybrid circuitry, and I guess that Mike Elliot would have used the ARC SP11/15 as a reference for his own designs. Tube purists may have scoffed at the hybrid ARC products, but the people who make a living out of reviewing them, raved about it.
However, the Alta Vista upgrades for the SA 5000 and SA 9 involves removing the SS buffers and cathode JFETs, and associated circuitry. Any assistance in providing feedback and guidance on tackling these mods would be greatly appreciated.
Thanks in advance.


ozdiyer
ozdiyer OP
6 posts
 
Thanks guys, I have all the Alta Vista upgrades stuff and will try swapping the JFET with a cathode resistor . 

nsp
653 posts
 
No circuit diagrams were provided when I upgraded and Elliot did not make a set of specs/diagrams available  for upgrades  when he closed down the site. 
You need to get those jfets out of there . the Sowter 8055  used in my unit gives a gain of 10 times & sounds great. You can change the loading resistors to get different loading values tailored to your needs. I had it done.  You need to go higher than 47k ?
You really should mod that unit . You will not believe how much different and better it sounds. 
I do have the name and address of Eliiot*s  last technician who worked on my unit. No phone or email info as all my contact was with Michael.  He probably has instruction/ schematics . Don*t know if he could/would help you ..
nsp
653 posts
 
i also wanted to ask what tubes you are using. Getting some new tubes can make a big difference. 
ozdiyer OP
6 posts
 
I have 4- NOS Amperex 6922 gold pin 1972 made in Holland. I am going to fit Keystone micro- jacks on the jack board so I can swap resistors to get the right loading for the Decca cartridge. I also have schematic for the SA 5, that could be an option after I remove the JFET and upgrade the coupling caps to Dynamicaps. I don't use the phono all that much since I am getting incredible sound from digital after upgrading the CD player and DAC last year. I had a Koetsu red MC , but I prefer the Garrott- Decca Gold which is in a class of its own, but needs careful set up. 

nsp
653 posts
 
the Amperex NOS tubes are a good choice. I am using 6 Siemens NOS  6922s and a Tele NOS 12AX7 in the power supply  spot  but that is my preference.
The SA5 schematic should help you. In a conversation with Mike Elliot he stated that the circuit in the SA5 AND SA5000 were pretty much the same except for the extra bells and whistles on the SA5000. Good luck with your changes / upgrades.
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